A number of techniques have been developed that involve placing a biological sample onto a substrate. Examples of these techniques include placing tissue samples from biopsies onto microscope slides, and micro-array analysis of samples. In histology, biological samples are attached to a microscope slide and stained to enhance the visibility of features of the tissue. Examples include routine staining, using haematoxylin and eosin stains to improve visibility of cell walls and the cell nucleus. In advanced staining, antibodies are applied to the tissue and then stained to identify the presence or absence of particular proteins, which may be indicative of disease. Other reagents may be applied to tissue such as RNA/DNA probes, which, during a sequence of reactions on the tissue, may bind to DNA in the cell nucleus. The hybridised DNA may then be stained to identify presence or absence of DNA of interest.
The number of proteins that may be used in investigation, research or diagnosis is large, and ever increasing. Similarly, the number of genes of interest is also increasing. If an automated instrument is to apply the wide range of reagents used in diagnosis or research, then the instrument must have flexibility. However, it is also important that samples are completed quickly and efficiently.
One instrument that is used to test slides is the Bond-max automated advanced staining instrument sold by Leica Microsystems, and described in application number WO 04/001390A1: BIOLOGICAL REACTION APPARATUS WITH DRAINING MECHANISM. A robotic arm is used to dispense reagent onto the slides located onto the instrument. The slides are loaded into the instrument in batches, which provides flexibility, as the instrument can start processing a first batch before a second batch is loaded. The capacity of the instrument, and its ability to process multiple batches simultaneously, is limited by the number of batches, the protocols and processing time of each slide, and the speed of the robotic arm in completing its tasks. There is a need to increase the flexibility of automated staining instruments, such as by decreasing processing time for slides, including batches of slides.